181se questions

[jscb1bb1b]

Why are single skinny ringed pistons better? More rpm? More compression? How does the ignition system work? Thank you!

 

[Bob Hedgecutter]

Less surface contact = less drag, less friction.

Does not have any bearing on ignition.

 

[jscb1bb1b]

Thank you for your response. Why does the 181 have two coils? What does the one by the flywheel do and what does the little one by the carb do?

 

[Bob Hedgecutter]

Thank you for your response. Why does the 181 have two coils? What does the one by the flywheel do and what does the little one by the carb do?

The big one down by the flywheel collects the charge and the wee one in the air box is the trigger unit that releases the charge to the HT lead and spark plug.

 

[Czed]

I ran a lot of 181s they were quite strong compared to 281s for some reason.

 

[Cliff R]

I would agree. 181SE's and strong runners for the CC's. I had one for quite a while but didn't find myself using it much. I observed a guy with a stock one once at a "get-together" running one in timed cutting and it was amazingly fast. Very few saw there, ported or bigger CC's would even come close to it.......

 

[Huskvarna hotellgäst]

The big one down by the flywheel collects the charge and the wee one in the air box is the trigger unit that releases the charge to the HT lead and spark plug.

Not quite right. The small module contains the voltage multiplier, The spark timing is triggered by the flywheel magnet passing the third leg on the large module.

 

[jscb1bb1b]

So the small module is a transformer?

 

[Huskvarna hotellgäst]

So the small module is a transformer?

I don't know for sure but I doubt it's a transformer, at least not only a transformer. (Can't find any old "Svenska Elektro-Magneter" documentation.). More likely some kind of insulated-gate transistor voltage multiplier.

 

[ballisticdoughnut]

I don't know for sure but I doubt it's a transformer, at least not only a transformer. (Can't find any old "Svenska Elektro-Magneter" documentation.). More likely some kind of insulated-gate transistor voltage multiplier.

I like to think of the two piece ignitions as a separate primary and secondary. Primary (flywheel) generates the low voltage, secondary (spark plug) steps it up to high voltage. I’ve got a few of the “secondary” coils with clear potting compound. All I can see is a whole lot of very fine copper wire. I’ll dig one up and take a picture.

 

[Bob Hedgecutter]

Not quite right. The small module contains the voltage multiplier, The spark timing is triggered by the flywheel magnet passing the third leg on the large module.

No it is not quite right- but it is a dumbed down version of a complicated explanation of events.

 

[Agrarian]

I believe the small one by the carb is a true coil (transformer) with one leg of each winding (primary & secondary) sharing a common ground. As the others said, the block by the flywheel is not truly a coil, it's an electronic module that is responsible for producing the properly timed current pulse to the coil's primary.

 

[ballisticdoughnut]

No visible electronics inside. Just fine copper windings. Should also add this is a 61/266 part not 181 but theory of operation is the same.

 

[jscb1bb1b]

Is there a proper way of testing the ignition system?

 

[Agrarian]

Testing the coil can be done with an ohmmeter but I don't have the values offhand. That will test for opens and significant shorted windings but will not pick up lesser shorts or compromised wire insulation that breaks down at high voltage. I don't know of a way of testing the module near the flywheel without mating it with a known good coil and testing for spark.

 

[Huskvarna hotellgäst]

No visible electronics inside. Just fine copper windings. Should also add this is a 61/266 part not 181 but theory of operation is the same.

Only reason I think the voltage multiplication might be more electronic in the 181 than the 266 is (a) the smaller size of the 181 secondary unit and (b) the 8 year difference in technology between the 2 - but I am only speculating.

 

[Agrarian]

Only reason I think the voltage multiplication might be more electronic in the 181 than the 266 is (a) the smaller size of the 181 secondary unit and (b) the 8 year difference in technology between the 2 - but I am only speculating.

I don't understand the 8 year difference you mention. The 181 IPL's run from '82 - '85 and the 266 IPL's run from '81 - '90 so they largely overlap. I don't believe either model received major coil changes over their manufacturing lifetime.

 

[Huskvarna hotellgäst]

I don't understand the 8 year difference you mention. The 181 IPL's run from '82 - '85 and the 266 IPL's run from '81 - '90 so they largely overlap. I don't believe either model received major coil changes over their manufacturing lifetime.

No problem. The 266 ignition uses the same ignition as the 162, which was introduced in 1976.

 

[Agrarian]

No problem. The 266 ignition uses the same ignition as the 162, which was introduced in 1976.

Ahhhh, that's what I was missing.